He had struck a deal to sell his software company, Autonomy, to Hewlett-Packard for an eyewatering $10.3bn (£6.6bn), a 59pc premium on its share price at the time.

There were slaps on the back for the Cambridge University graduate, as he took $800m off the table for his stake in the FTSE 100 business which he founded in 1996, based on research he had begun during his PhD in mathematical computing.

Autonomy had cracked the thorny problem of how to search so-called “unstructured data” – voicemail, emails, fragments of information on social networks – anything which cannot be parcelled into a traditional database or spreadsheet.

Instead of requiring users to enter rigid search terms to look for information, Autonomy’s sophisticated data recognition software could search data based on its meaning. Companies paid a fortune to use the software for internal investigations and compliance procedures.

But not everyone was convinved of Autonomy’s brilliance. Mr Lynch, 46, had had a notoriously rocky relationship with investors and analysts, some of whom were as sceptical about Autonomy’s accounting policies as they were about its products.

One analyst who criticised the firm for counting research and development investment as an asset on its balance sheet, rather than a cost to be written down, was banned from meetings. Meanwhile, a steady stream of acquisitions made it very difficult to decipher Autonomy’s underlying growth. “Some companies put all their goods in the shop window. Some hold them back a bit. Autonomy is one of the former,” said Tim Steer, a fund manager at Artemis.

For some analysts, Autonomy was an emperor’s new clothes-style triumph of style over substance. Mr Lynch gave them short-shrift. If they didn’t agree with his valuation of the company, it was because they simply didn’t understand.

The HP deal, when it came, was vindication of more than 16 years of evangelism. One of the giants of the US technology industry had rolled out the red carpet Mr Lynch thought he so richly deserved.

The self-confessed workaholic was feted as Britain’s answer to Bill Gates and swapped his offices in London and Cambridge, for the sunnier climes of Silicon Valley.

That threads of the red carpet started to unravel very fast, however. Shares in Hewlett-Packard crashed 20pc the day after the deal. A month later, HP’s chief executive and president Léo Apotheker was ousted, amid shareholder concern over the Autonomy price tag, as well as a profit warning and a the spectre of a major strategy shift away from making computers.

It later emerged that he had fallen out with HP's finance director, Cathie Lesjak, prior to the Autonomy acquisition because she thought the price was too high.

Since the deal, up to a quarter of Autonomy's staff have left, including senior finance and marketing executives, it was reported.

Nonetheless, Meg Whitman, who replaced Mr Apotheker, pressed ahead with the Autonomy acquisition. Growing the company was her “priority one, two and three”, she said as she presided over her first set of results last November.

Mr Lynch told his peers that HP understood that “Autonomy is high-speed, smaller and more agile and it needs to be left that way”.

Just six months later, after the close of trading on Thursday night, the honeymoon came to an abrupt end. Ms Whitman said Mr Lynch would be leaving, after “classic entrepreneurship challenges” led to “very disappointing” results at Autonomy. HP might have shelled out more than $10bn on a software company, but its software revenues were flat.

Mr Lynch’s defensive stance did not have much traction with his new boss, unless he had the figures to back it up.

In case anyone was in any doubt about what had gone wrong, Ms Whitman added: “It is not the product. It’s not the market. It’s not the competition. This is classic entrepreneurial company scaling challenges – it’s a whole different ball game.”

Bill Veghte, HP’s chief strategy officer and former big-hitter at Microsoft, has been tasked with sorting Autonomy out - leaving Mr Lynch with $800m tucked in his back pocket, and his tail between his legs.